1. Technical Field
The present invention relates to a system for remote control of at least an appliance, the system comprising a remote control and an extender coupled thereto. The present invention also relates to a method for remote control of at least an appliance in a system comprising a remote control and an extender coupled thereto.
2. Description of Related Art
A network infra red (IR) extender is a device specially designed to extend the coverage of a regular remote control, still using standard IR receivers for the appliances. The extender is able to reach the receiver of the appliance, for example because it is located in line of sight of the receiver, while the Remote Control (RC) is not able to reach the receiver. Remote control extender systems are particularly useful for control of hidden (e.g. built-in) devices in the same room or for control of appliances in another room. Also the combination of multiple extenders permits the control of multiple appliances at the same time without the need to move the RC around in different directions. The remote control is coupled to the extenders via a (home) network.
An existing network extender system of Philips uses a connection-based IP protocol, the Transmission Control Protocol (TCP), to communicate the commands between the RC and the extender. The remote control of this system is available under the product name TSi6400 and the extender of this system is available under the product name NXT6400. A connection-based protocol such as TCP is designed to reliably deliver the data to a peer device using acknowledgements, retransmissions and congestion control to reduce the transmission errors over congested networks. As a consequence, a connection-based protocol does not provide timely data delivery. Indeed, the protocol depends on network behavior and, if necessary, it will retransmit the same data multiple times to ensure guaranteed delivery in detriment of time constrains. In that context a RC cannot guarantee the time at which a command is delivered to an extender.
While the connection-based protocol works mostly well on a wired home network, it suffers significantly from perturbation of a wireless home network.
The requirement for time control of command execution is critical in the context of repeat commands. Repeat commands have a variable time duration. A repeat command 10 according to the state of the art is described with reference to FIG. 1. A repeat command is a special command that begins with a special start code (S), continues with continuation codes (C) and optionally finishes with an end code (E). Each code represents a single instruction for the appliance. The start code instructs the receiver of the appliance to start an operation that is maintained as long as the continuation code is sent to the receiver. Finally, the optional end code may be used to close the repeat command. Furthermore, the start code and the continuation code of the repeat command may be the same.
As an example, the user action Volume UP is executed by a repeat command. The start code requests a volume up. The volume is raised further by a predetermined dB value as long as the continuation code is received by the appliance. The receiver knows to stop incrementing volume when the continuation code is not received anymore.
The RC repeat command duration is determined by the time interval between depressing (t1) and releasing a key/button (t2). The duration of a repeat command is critical and must be respected, as it is the receiver of the appliance that interprets the duration in its context. For example, using a repeat command a receiver will be able to differentiate a stop ( ) action from an eject request on DVD player. A short repeat command duration meaning ‘stop’, while a longer repeat command duration request the DVD player to stop and open the disc tray.
The errors of repeat command duration, in particular for repeat commands executed over an IP network by a TCP connection are critical. Sometimes, the duration may be even 3 seconds longer than expected. This means that the IR extender will transmit volume UP for 3 additional seconds after the user has released the key of the remote control.
It is an object of the invention to control the duration of commands with a variable time duration in a remote control system with an extender.